Mordenite has been suggested for use as cracking catalysts (see Breck, "Zeolite Molecular Sieves", Wiley and Sons (1974), pages 122-124, and pages 162-163).
The typical oxide formula of such mordenite may be composed of the following molar oxide ratios: EQU Na.sub.2 O:Al.sub.2 O.sub.3 :10 SiO.sub.2
and the Si/Al ratio may vary from 4 to 5 (see Breck, page 162, supra).
The sodium content may be reduced by exchange. Thus the hydrogen form may be produced through exchange with acids or ammonium salts followed by calcination (see U.S. Pat. No. 3,527,826).
Applicants have found that they may produce superior results in the case of the zeolites of the faujasite type by exchanging the zeolite under pressure. They have been able to reduce the sodium content of the zeolite and improve its hydrohydrothermal stability by exchanging the zeolite under autogenious pressure above the normal boiling point. This may be done without materially adversely affecting the crystalline structure of the zeolite (see U.S. Pat. No. 4,058,484 filed Sept. 9, 1976 patented Nov. 15, 1977 and U.S. Pat. No. 4,085,069) filed Aug. 27, 1976, patented Apr. 18, 1978. See also, applications Ser. No. 808,268, filed June 20, 1977; Ser. No. 869,856, filed June 16, 1978 now U.S. Pat. No. 4,192,758; and Ser. No. 874,754, filed Feb. 3, 1978 now U.S. Pat. No. 4,164,483.